Neoconservatives and hardline nationalists in the US wanted to invade Iraq for three reasons - it was an established bogeyman in US minds, it would be an easy target, and it would provide a potential base from which the US could permanently dominate the Gulf region and, if need be, deny oil to China.

In sum, the US invasion was not driven by Middle East considerations at all - it had more to do with the emergence of China. That is the interesting theory at the start of Gwynne Dyer's book After Iraq: what next for the Middle East?

Published to coincide with the fifth anniversary of the invasion of Iraq, the book is concise, incisive and thoroughly entertaining. At times, despite the serious subject matter, it is laugh out loud funny because of its irreverent style, not least in the way it debunks what pass for established facts.

Take Mahmoud Ahmadinejad's call for Israel to be wiped off his map. Dyer points the reader to a translation of the 2006 speech by Juan Cole, a professor and respected blogger, who offers this version of the offending statement:

"The imam said that this regime occupying Jerusalem must [vanish from] the pages of time". For Dyer, what Ahmadinejad was calling for was an end to the "Zionist regime" in Israel, not for the extermination of the Jewish people.

With opinions like this, it is no wonder that Conrad Black, the former media magnate now in jail, dropped Dyer's column from the Jerusalem Post and other Canadian publications he owned.

Dyer, a Canadian academic turned journalist, has little time for the fashionable theory of the "Shia crescent" or the fear of Shia expansion in the Arab world at the expense of the majority Sunnis now Shias dominate Iraq as well as Iran.

The notion of an Iranian military threat to the Arab world belongs to the realm of fantasy.

The regional balance of power has shifted and Iran has much more weight than it used to, but this does not mean that Iranian armoured divisions will soon be racing across the Fertile Crescent and seizing the Arab oil fields on the Arab side of the Gulf.

For one thing, Iranian armoured divisions do not race; they move at an arthritic crawl ... for another why would Iran want to rule some tens of millions of rebellious Arabs and a bunch of burning oil fields.

Dyer believes the US has lost the war in Iraq and will soon be pulling out, notwithstanding any success from the troop "surge".

Getting out of Iraq, he argues, is the least bad thing for the US - and the sooner the better. He sees a serious possibility that the US will not only retreat from Iraq, but very substantially reduce its military presence in the entire Middle East - "not necessarily a Bad Thing for the region, or the world".

The Middle East desperately needs change from its stagnant state, which is not solely the fault of the US, Dyer says, but American presence and policies have upheld the status quo of authoritarian and corrupt regimes.

But what about the Islamists waiting in the wings?

Dyer does not believe Arabs will vote for radical Islamists if there is political liberalisation.

"Arabs are not fools, and most find it hard to believe that the solutions to all their problems were quite as simple as the Islamists contend," he argues.

The one place where they had a whiff of success was Algeria, where elections were cancelled when it looked as though Islamists would win.

During the ensuing civil war, the Islamists' barbaric tactics and extreme ideas turned popular opinion against them.